Selection of entomopathogenic fungi for the control of the western corn rootworm Diabrotica virgifera virgifera
2007
Pilz, C. | Wegensteiner, R. | Keller, S.
The western corn rootworm Diabrotica virgifera virgifera Le Conte (Col., Chrysomelidae), a serious pest of maize, has been recently introduced into Europe. Several approaches for its control are presently under investigation including microbial agents. During a field survey in Hungary in 2005, naturally occurring entomopathogenic fungi were found to attack this pest. These novel isolates together with standard isolates were tested for virulence against D. v. virgifera larvae and adults. Twenty strains of Metarhizium anisopliae, Beauveria bassiana and Beauveria brongniartii were used in bioassays in the laboratory. Larvae and adults were dipped into a spore suspension with a concentration of 1 x 10⁷ conidia (con.)/ml. They were kept for 14 days at 22°C (±2°C) and 70% relative humidity. The number of infected larvae and adults were counted and infection rates were calculated. Adults were significantly more susceptible to entomopathogenic fungi than larvae. The most virulent isolate infected about 47% of larvae (M. anisopliae Ma2277), whereas the infection rate in adults was up to 97% (M. anisopliae Ma2275). Isolates of M. anisopliae caused significantly higher mortalities than isolates of B. brongniartii and B. bassiana. Most of the adult beetles were killed within 12 days. Isolates from D. v. virgifera were more virulent than those from other hosts.
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